#define _CRT_SECURE_NO_WARNINGS  1


typedef char STDataType;

typedef struct Stack
{
	STDataType* a;
	int top;
	int capacity;
}ST;

void STInit(ST* ps);
void STPush(ST* ps, STDataType x);
void STPop(ST* ps);
int  STSize(ST* ps);
bool STEmpty(ST* ps);
void STDestroy(ST* ps);
STDataType STTop(ST* ps);

void STInit(ST* ps)
{
	assert(ps);
	ps->a = (STDataType*)malloc(sizeof(STDataType) * 4);
	if (ps->a == NULL)
	{
		perror("malloc fail");
		return;
	}
	ps->capacity = 4;
	ps->top = 0;
}

void STDestroy(ST* ps)
{
	assert(ps);

	free(ps->a);
	ps->a = NULL;
	ps->top = 0;
	ps->capacity = 0;
}

void STPush(ST* ps, STDataType x)
{
	assert(ps);
	if (ps->top == ps->capacity)
	{
		STDataType* tmp = (STDataType*)realloc(ps->a, sizeof(STDataType) * ps->capacity * 2);
		if (tmp == NULL)
		{
			perror("realloc fail");
			return;
		}
		ps->a = tmp;
		ps->capacity *= 2;
	}
	ps->a[ps->top] = x;
	ps->top++;
}

void STPop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));

	ps->top--;
}

int  STSize(ST* ps)
{
	assert(ps);

	return ps->top;
}

bool STEmpty(ST* ps)
{
	assert(ps);

	return ps->top == 0;
}

STDataType STTop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));

	return ps->a[ps->top - 1];
}

bool isValid(char* s)
{
	ST st;
	STInit(&st);
	while (*s)
	{
		if (*s == '{' || *s == '(' || *s == '[')
		{
			STPush(&st, *s);
		}
		else
		{
			if (STEmpty(&st))
			{
				return false;
			}
			char top = STTop(&st);
			STPop(&st);

			if ((*s == '}' && top != '{')
				|| (*s == ')' && top != '(')
				|| (*s == ']' && top != '['))
			{
				return false;
			}

		}
		++s;
	}
	bool ret = STEmpty(&st);
	STDestroy(&st);
	return ret;
}